Lines for the production of paper products such as tissues and napkins of various sizes typically have a stacking step in which the products, already folded up according to one of the possible configurations, must be picked up, as they arrive from the folding station, by conveyor means, for example belts or the like, and positioned precisely on each other to be then packaged in packs of a preset number of items.
This stacking operation is usually performed by using one or more star conveyors provided with peripheral receptacles in which the products which arrive from the conveyor means are inserted and by which they are then deposited one by one on a movable supporting surface which forms the stack which will then be packaged into a packet. The need to unload the stack from the supporting surface to make it reach the packaging station requires the star conveyor to remain periodically inactive for a given period of time.
Since transfer star conveyors cannot turn faster than a given limit which is set during design, in order to increase the production rate some packaging lines therefore use even more than one star conveyor: for example two star conveyors are used which are powered by the same conveyance means and work alternately with each other.
This last solution and other similar ones, however, are rather complicated in terms of design and manufacture and are usually adopted in large high-productivity lines which have very high installation and maintenance costs.